NVARCHAR(m,r) data type

The NVARCHAR data type stores strings of varying lengths. The string can include digits, symbols, and both single-byte and (in some locales) multibyte characters.

The main difference between VARCHAR and NVARCHAR data types is the collation order. Collation of VARCHAR data follows code-set order, but NVARCHAR collation can be locale specific, if DB_LOCALE (or SET COLLATION) has specified a locale that defines a localized order for collation. (The section Collating VARCHAR Values describes an exception.)

A column declared as NVARCHAR, without parentheses or parameters, has a maximum size of one byte, and a reserved size of zero.

The first parameter in NVARCHAR data type declarations can be affected by the SQL_LOGICAL_CHAR configuration parameter that is described in the section Logical Character Semantics in Character Type Declarations.

No more than 195 columns of the same table can be NVARCHAR data types.

In databases that are created with the NLSCASE INSENSITIVE property, operations on NVARCHAR strings ignore letter case, ordering data values without respect to or preference for letter case. For example, the NVARCHAR string "IBM" might precede or follow "IbM" or "iBm" in the collated list that a query returns, depending on the order in which these data strings are retrieved, because all of the following NVARCHAR strings are treated as duplicate values:
"ibm" "IBM" "ibM" "IBm" "IbM" "iBm" "iBM" "Ibm"